Grape 2 Personal Space Weather Station

The Grape 2 software defined receiver (SDR) is a key component of the HamSCI Personal Space Weather Station (PSWS).  The Grape 2 was designed with specific purposes in mind:  Receiving, analyzing and recording of signals from frequency standard stations such as WWV/H and CHU. The PSWS project involves monitoring changes in the Earth's ionosphere through measurements of Doppler frequency shifts on a 24/7 basis.

Ham radio operators and shortwave enthusiasts are encouraged to host Grape 2 SDRs at their stations from their time of release until well after the North American total solar eclipse in April of 2024.  Hosting involves providing reliable power, space for an antenna and an Internet connection.  Other factors come into play, such as the need for visibility to the constellation of GPS satellites. A Host Interest Survey is now being conducted.

A complete description of the PSWS, including an explanation of the science questions driving the need for the Grape 2 (and its little brother, the Grape 1) is available here.

The following is preliminary information.  The Grape 2 hardware is in the prototype/testing phase and the software is under development.  Features and specifications are subject to change.  Anticipated release: Q1, 2024

Anatomy of the Grape 2 PSWS

The Grape 2 is the high performance member of the Grape PSWS family.  It is capable of receiving three frequencies simultaneously and it contains an on-board GPS module/frequency standard.  It is designed for use on 2.5, 5.0, 10.0 or 15.0 MHz.  (Operation on CHU frequencies of 3.33, 7.58 and 14.36 MHz are possible with reduced performance.) The receiver PC board is delivered fully assembled.  The complete PSWS system requires the following: Grape 2 SDR, Raspberry Pi 3/4, external hard drive, power supply and antenna.  All components are documented below.  

Please note that the Grape receivers are not general purpose software defined receivers (SDRs). They are designed to receive signals only on frequencies pertinent to the research goals.

Images of the Grape 2 under development at the bench of John Gibbons, N8OBJ:



​Special Note to Those Who Are Currently operating a Grape 1 receiver (version 1.11 or 1.12):

The data formats will be different in the Grape 2 vs. 'legacy' Grape1s.  

Both data formats have research value.  If you are running, or considering running, a 'Legacy' Grape 1, the data generated has been and will continue to be quite useful to the research community.


The Grape Version 2 is being designed by John Gibbons, N8OBJ, Lab Director of the Sears Undergraduate Electrical Design Lab, Case Western Reserve University, Department of Electrical Engineering.  Software is being written by Cuong Nguyen, KC3UAX and Bill Blackwell, AB1XB.  Their efforts are being supported by a number of institutions and foundations

Supporting Institutions